The present invention relates generally to surface coverings. In particular, the invention relates to a mechanically and chemically embossed surface covering having a selectively textured surface.
Decorative laminate surface coverings can be formed into sheets or individual tiles. Typically, in the manufacture of a resilient floor covering, a wear layer is combined with a substrate and resin to form the resilient sheet or tile. The substrate usually comprises a felted or matted fibrous sheet of overlapping, intertwined filaments or fibers. A substantially uniform layer of a liquid or semi-liquid resinous composition containing a synthetic polymeric material, usually an ungelled polyvinyl chloride plastisol and a blowing or foaming agent is typically applied to the substrate. The liquid or semi-liquid plastisol vinyl resin composition is subsequently firmed or gelled at an elevated temperature. This gelled plastisol may be printed with a decorative pattern or design having a blowing or foaming inhibitor for chemically embossing the substrate.
Decorative laminate surface coverings are often designed to have textured surfaces patterned to duplicate a look of actual wood, tile, brick, stone, and other such products. Typically, the texture is either mechanically embossed by pressing a pattern into the surface covering or chemically embossed by using foam retarding agents to restrict expansion of a foamable layer in specific regions of the design. Although these methods provide attractive decorative surface coverings, they are limited in their capability to replicate the appearance of the actual product.
There continues to be a demand by consumers for surface coverings that have a xe2x80x9cmore realisticxe2x80x9d appearance to the natural product. U.S. Pat. No. 5,961,903 describes one method of manufacturing an embossed resinous foam product which is both chemically and mechanically embossed, and includes forming a foamable, resinous composition which contains a blowing agent. An ink composition having a blow modifying agent/retarder is printed onto the foamable, resinous composition. A wear layer is applied and the wear layer/foamable composition is heated to expand the foam and cure the wear layer. Areas of the foam printed with the printing ink composition are restricted from expanding resulting in a chemically embossed product. The chemically embossed structure is cooled to ambient temperature before any further handling. Thereafter, the chemically embossed product is reheated and a texture is mechanically embossed, using an overall textured embossing roll, into the hot wear layer overlying the non-restricted/up foam regions by pressure while it is relatively soft, plastic, and moldable. After the foam is mechanically embossed and has cooled to ambient temperature, a wear layer is coated and cured onto the chemically and mechanically embossed foam.
An alternative method for making a chemically and mechanically embossed surface covering (Armstrong U.S. Ser. No. 09/770,582 incorporated in by reference), includes coating a backing layer with a foamable layer, and adding a print layer to it. The print layer forms a design and a portion of the design is formed with a retarder composition. A thermoplastic wear layer is applied onto the print layer and cured by heat at a temperature sufficiently high enough to expand the foamable layer. The areas of the design layer where the retarder composition is applied are also chemically embossed during such curing. In a continuous process and without cooling to ambient conditions, the temperature of the cured thermoplastic wear layer is adjusted by heating, and the wear layer is then mechanically embossed to have a surface texture in the wear layer overlying the unrestricted/up areas. Optionally, a top coat can be applied to the wear layer before curing and expanding the foam, and the top coat can be mechanically embossed.
Despite existing methods of making chemically and mechanically embossed surface coverings, there is a need for a surface covering having a chemically embossed foam layer and a selectively textured top coat wear layer for simulating a natural product.
Briefly described, the present invention comprises a method of manufacturing a mechanically and chemically embossed surface covering. In one embodiment of the present method, a mechanically and chemically embossed surface covering is made comprising forming a web having a substrate, an expandable foam layer, and at least one inhibitor/retarder or activator composition disposed as a pattern proximate the foam layer. The web is coated with a wear layer to form a coated web. The coated web is heated to a temperature at which the wear layer is cured, the foam layer expands, and the pattern is chemically embossed to form a surface covering having foamed regions and nonfoamed or restricted regions. The temperature gradient of the surface covering is adjusted such that there is a difference between the foamed and non-foamed regions. At least one surface texture is mechanically embossed onto the wear layer with the surface texture being predominantly set onto the wear layer, which substantially overlies the nonfoamed regions.
In greater detail, the surface covering is subjected to an overall textured mechanical embossing roll nip. In one embodiment the embossing roll can have two or more different textures. The temperature gradient is adjusted such that the wear layer over the nonfoamed or restricted regions is mechanically textured, and the wear layer over the foamed regions is substantially non-textured. The surface texture is set into the wear layer residing predominantly over the nonfoamed regions.
Another aspect of the present invention relates to a method of manufacturing a mechanically and chemically embossed surface covering comprising a top coat. The method includes forming a web comprising a substrate, a curable wear layer, and an expandable foam layer between the substrate and the wear layer. Additionally, at least one inhibitor or activator composition is disposed on the covering as a pattern proximate the foam layer. The wear layer of the web is coated with a cross-linkable top coat to form a top coated web. The top coated web is heated to a temperature at which the top coat is substantially cross-linked and cured, the wear layer is cured, the foam layer expands, and the pattern is chemically embossed to form a surface covering having foamed and nonfoamed regions. The temperature gradient of the surface covering is adjusted such that there is a difference between the foamed and non-foamed regions. At least one surface texture is mechanically embossed onto the wear layer and the surface texture is predominantly set into the wear layer substantially overlying the nonfoamed regions.
A further aspect of the present invention relates to a method of manufacturing a mechanically and chemically embossed surface covering by back heating the covering. The method includes forming a web comprising a substrate, an expandable foam layer, and at least one inhibitor composition disposed as a pattern proximate the foam layer, and coating the web with a wear layer to form a coated web. The coated web is then heated to a temperature at which the wear layer is cured, the foam layer expands, and the pattern is chemically embossed to form a surface covering having foamed regions and nonfoamed or restricted regions. Heat is then applied to the substrate side of the surface covering or the backside of the covering. The resulting face temperature of the substrate side is greater than that of the wear layer. At least one surface texture is mechanically embossed onto the wear layer. The surface texture is set into the wear layer areas residing predominantly over the nonfoamed or restricted regions of the surface covering.
Furthermore, there is included a chemically and mechanically embossed surface covering. The surface covering comprises a substrate and a foam layer disposed on the substrate. The foamed layer has a chemically embossed pattern having foamed regions and non-foamed or restricted regions imposed thereon. xe2x80x9cFoamed regionsxe2x80x9d correspond to xe2x80x9cup areasxe2x80x9d of the chemical embossing, and the xe2x80x9cnon-foamed regions correspond to the xe2x80x9cdown areasxe2x80x9d of the chemical embossing. Although no foaming is preferred in the xe2x80x9cdown areasxe2x80x9d to impart the deepest chemical embossing effect, some amount of foaming (partial foaming) may occur in the xe2x80x9cnon-foamed regionsxe2x80x9d dependent upon chemical embossing conditions. Therefore, xe2x80x9cnon-foamed regionsxe2x80x9d also include partial foamed regions as long as they impart a chemical embossing effect. A wear layer is disposed on the foamed layer, and a surface texture mechanically embossed and selectively set into the wear layer areas residing predominantly over the non-foamed or restricted regions.